This paper discusses the development of an active real-time control method for steam exciting vibration of blade tip clearance seals. Based on LABVIEW, a closed loop system for flow regulation is developed, in which air jets or suction can be adjusted according to different blade vibration amplitudes. The experimental research on vibration suppression due to suction is under two kinds of seal conditions, smooth seal and honeycomb seal. The results indicate that the suction flow rate is regulated in real time as the blade vibration varies, and the amplitude of blade vibration is controlled at the threshold range that is set according to operating conditions. The suppressing effect of closed loop controlled suction is up to 30% with the smooth seal, and 40% with the honeycomb seal. The suppressing effect is better when both active control and passive control are combined.